Why this is not in Default FF ??Rated 5 out of 5 stars

This addon is what i think is must to have , indeed it should be a default in Firefox . The Best thing about this addon is easily customizable styles of tabs with userChrome.css and the brilliant/Simple API support which is very useful for me to create custom Firegestures scripts with ease .

Bcoz of this no need to open a new Window do check private Browsing. Thanks to developer for providing this addon.